In walls formed of plaster boards, sheet rock, plywood and other relatively thin or soft materials, problems can arise when attempting to mount objects to these walls, particularly transverse rods for draperies, drapes, lighting fixtures, picture frames and other objects which impose stress upon these walls. These walls can be incapable of receiving the aforementioned rods, fixtures and frames when held in place by standard screws and bolts. Thus, it has become common practice to use anchoring sockets of some sort in order to secure these objects to a wall. A number of wall anchors are noted in the prior art, particularly U.S. Pat. Nos. 4,646,998; 4,752,170; 5,409,339; 5,533,851; and 6,086,035.
Prior art wall anchors, or back clips as they are otherwise known, such as disclosed in U.S. Pat. No. 4,669,936, teach a back clip having a body portion with a hollow barrel therein and laterally expandable fingers in alignment with the hollow barrel. The fingers extend through a wall and upon receiving a bolt, pin, screw or other securing member through the barrel, the laterally expandable fingers expand against the inside portion of the wall.
Common wall anchors, such as the one taught by U.S. Pat. No. 4,669,936, have a straight channel separating the fingers. This channel is usually narrower than the hollow barrel portion, so that when the securing member is inserted, it expands the fingers, securing the wall anchor to the wall. When these fingers are expanded they necessarily bend or hinge at some point on the finger, usually at a point at or near where each finger is connected to the hollow barrel. This hinge portion of the fingers is thus normally under some amount of stress due to the deformation that takes place in the wall anchor when the bolt, pin or screw is introduced into the wall anchor. Because of this stress, harder, more rigid plastics, the most preferred material of construction for wall anchors, tend to break in this hinge area, particularly when used in cold-weather. Softer plastics are commonly used to avoid this breakage problem, but may correspondingly reduce the strength of the wall anchor.
Referring to FIG. 1, a prior art wall anchor 2 is shown. Wall anchor 2 of FIG. 1 includes a generally flat circular head 4 having a bore therethrough (not shown) for receiving a securing member, such as a bolt, pin, screw, nail or similar object (not shown). Wall anchor 2 also contains a barrel 6 having a bore therethrough (not shown) and a pair of symmetrical fingers 8a and 8b flexibly joined to the barrel 14 at its back end. A generally straight channel 10 separates the two symmetrical fingers 8a and 8b. FIG. 2A shows a view of the prior art wall anchor from the front, and, looking through the bore in head 4, channel 10 is visible between the two symmetrical fingers 8a and 8b. 
FIG. 2B shows the prior art wall anchor 2 in its secured position in a wall 16. The bores through the barrel 6 and the head 4 receive a securing member, in this case a mounting pin 14, therethrough. When the mounting pin 14 is inserted into the wall anchor, the pin engages and spreads the fingers 8a and 8b apart. The portions 12a and 12b, where the fingers 8a and 8b attach to the barrel 6, are under a considerable amount of stress due to the deformation that takes place when the fingers are expanded.
It would thus be desirable to develop a wall anchor designed to reduce stress in the hinge portion of the fingers. This type of wall anchor would allow for the use of harder, more rigid plastics, resulting in a stronger anchor less susceptible to breakage.
A wall anchor has a body portion having a hollow barrel and laterally expandable fingers in general alignment with the hollow barrel. Instead of using a straight channel separating two symmetrical fingers, as is commonly used in prior art wall anchors, an asymmetrical channel is used to provide at least two ramp surfaces, one on each of a plurality of asymmetrical fingers, i.e. none of the fingers are the same shape. The ramp surfaces face the path created by the hollow portion of the barrel. Thus, when a securing member, such as a bolt, pin, screw, nail or other similar object, is inserted into the hollow barrel to secure the wall anchor to the wall, the securing member contacts the two ramp surfaces. As the securing member is pushed through the hollow barrel and into the curved channel, it separates the fingers. As the fingers separate, the ramp surfaces deform under the pressure exerted by the securing member, and then rest on an outer portion of the securing member.
This design thus allows for a redistribution of the stress from a hinge portion of the anchor to the ramp surfaces of the fingers when the fingers are separated. This allows the wall anchor to be manufactured from harder, more rigid materials, thereby improving the strength of the wall anchor and reducing its susceptibility to breaking.